t'box adjustment?

[lambert]

on the top of my t'box there is a cover hel down by 6 bolts from which the high low selector shaft emerges. is there anything underr there that can be tightened to give a more possitive throw to the high low lever, only i seem to need more movement to engage low or high than there is adjusment in the linkage between lever and box.

any help would be good.

[Range Rover Blues]

Could be something has come loose like a pin throught the selector fork.